This disclosure describes techniques of configuring capacitive comb fingers of an accelerometer resonator into discreet electrodes with drive electrodes and at least two sense electrodes. The routing of electrical signals is configured to produce parasitic feedthrough capacitances that are approximately equal. The sense electrodes may be placed on opposite sides of the moving resonator beams such that the changes in capacitance with respect to displacement (e.g. dC/dx) are approximately equal in magnitude and opposite in sign. The arrangement may result in sense currents that are also opposite in sign and result in feedthrough currents of the same sign. The sense outputs from the resonators may be connected to a differential amplifier, such that the difference in output currents may mitigate the effect of the feedthrough currents and cancel parasitic feedthrough capacitance. Parasitic feedthrough capacitance may cause increased accelerometer noise and reduced bias stability.

A system and method for providing a MEMS sensor are disclosed. In a first aspect, the system is a MEMS sensor that comprises a substrate, an anchor region coupled to the substrate, at least one support arm coupled to the anchor region, at least two guiding arms coupled to and moving relative to the at least one support arm, a plurality of sensing elements disposed on the at least two guiding arms to measure motion of the at least two guiding arms relative to the substrate, and a proof mass system comprising at least one mass coupled to each of the at least two guiding arms by a set of springs. The proof mass system is disposed outside the anchor region, the at least one support arm, the at least two guiding arms, the set of springs, and the plurality of sensing elements.

The disclosure describes techniques to damp the proof mass motion of an accelerometer while achieving an underdamped resonator. In an example of an in-plane micro-electromechanical systems (MEMS) VBA, the proof mass may contain one or more damping combs that include one or more banks of rotor comb fingers attached to the proof mass. The rotor comb fingers may be interdigitated with stator comb fingers that are attached to fixed geometry. These damping comb fingers may provide air damping for the proof mass when the MEMS die is placed into a package containing a pressure above a vacuum. The geometry of the damping combs with a reduced air gap and large overlap area between the rotor comb fingers and stator comb fingers. The geometry of resonator of the VBA of this disclosure may be configured to avoid air damping.

The disclosure describes techniques to adjust the geometry of a pendulous proof mass VBA to operate with sufficient signal-to-noise performance while avoiding nonlinear mechanical coupling at specified frequencies. The techniques of this disclosure include adding anchor support flexures to a resonator connection structure, adjusting shape, thickness, and the material of VBA components and of the VBA support structure to both control the frequency of any mechanical resonant modes and to adjust the mechanical mode frequencies away from desired operating frequencies and, in some examples, away from harmonics of desired operating frequencies.

The present invention provides a high-accuracy low-noise MEMS accelerometer by using a larger, single proof mass to measure acceleration along two orthogonal axes. A novel arrangement of electrodes passively prevents cross axis error in the acceleration measurements. Novel arrangements of springs and a novel proof mass layout provide further noise reduction.

A micromechanical z-inertial sensor includes a substrate; a movable seismic mass in a micromechanical functional layer; a torsion spring connected to the movable seismic mass and about which the seismic mass able to rotate; an electrode layer below the seismic mass and that, in an outer region is connectible to a potential of the substrate and is connected to the seismic mass via an insulating layer; and electrodes at a distance above and below an inner region of the electrode surface.

The disclosure describes techniques to adjust the geometry of a pendulous proof mass VBA to operate with sufficient signal-to-noise performance while avoiding nonlinear mechanical coupling at specified frequencies. The techniques of this disclosure include adding anchor support flexures to a resonator connection structure, adjusting shape, thickness, and the material of VBA components and of the VBA support structure to both control the frequency of any mechanical resonant modes and to adjust the mechanical mode frequencies away from desired operating frequencies and, in some examples, away from harmonics of desired operating frequencies.

This disclosure describes techniques of configuring capacitive comb fingers of an accelerometer resonator into discreet electrodes with drive electrodes and at least two sense electrodes. The routing of electrical signals is configured to produce parasitic feedthrough capacitances that are approximately equal. The sense electrodes may be placed on opposite sides of the moving resonator beams such that the changes in capacitance with respect to displacement (e.g. dC/dx) are approximately equal in magnitude and opposite in sign. The arrangement may result in sense currents that are also opposite in sign and result in feedthrough currents of the same sign. The sense outputs from the resonators may be connected to a differential amplifier, such that the difference in output currents may mitigate the effect of the feedthrough currents and cancel parasitic feedthrough capacitance. Parasitic feedthrough capacitance may cause increased accelerometer noise and reduced bias stability.

The disclosure describes techniques to damp the proof mass motion of an accelerometer while achieving an underdamped resonator. In an example of an in-plane micro-electromechanical systems (MEMS) VBA, the proof mass may contain one or more damping combs that include one or more banks of rotor comb fingers attached to the proof mass. The rotor comb fingers may be interdigitated with stator comb fingers that are attached to fixed geometry. These damping comb fingers may provide air damping for the proof mass when the MEMS die is placed into a package containing a pressure above a vacuum. The geometry of the damping combs with a reduced air gap and large overlap area between the rotor comb fingers and stator comb fingers. The geometry of resonator of the VBA of this disclosure may be configured to avoid air damping.

A physical quantity sensor includes a first plate, and a second plate opposed to the first plate via a gap, wherein a sensing area in which the gap between the first plate and the second plate changing with a physical quantity is detected based on a change of a capacitance is disposed in an area where the first plate and the second plate overlap each other in a plan view, the first plate is provided with a through hole in the sensing area, and in a part of the second plate where the second plate overlaps the through hole of the first plate in the plan view, a distance from the second plate to an imaginary plane extending in a same plane as a surface of the first plate opposed to the second plate via the gap is longer than a distance of the gap.